Apparatus for coating simultaneously a plurality of separate metal articles



D. W. COLAS 0R COAT ANTO ING SIMULTANEOUSLY A PLURALI Nov. 25, 1958 APPARATUS F OF SEPARATE METAL ARTICLES Filed Dec.

IN l E NTOR.

APPARATUS FOR COAT-"ENG SIMULTANEOUSLY A PLURALITY F SEPARATE METAL ARTICLES Dominick William Colasanto, Ridgefield, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application December 23, 1953, Serial No. 399,995 2 Claims. (Cl. 204-199) The present invention relates to an improved apparatus and method for coating a plurality of separate metal articles or units by electrodepositions.

An object of the invention is to increase the speed of selectively coating by electrodeposition a plurality of metal articles in one coating operation.

Another object is to provide a coating apparatus having an electrode adapted to engage simultaneously predetermined portions of a plurality of metal articles for coating other portions of the articles by electrodeposition.

A further object is to provide a deformable electrode adapted to engage a plurality of unevenly arrayed metal units for coating said units by electrodeposition.

Another object is to provide an apparatus and method for simultaneously coating by electrodeposition predetermined portions of lead-in wires of a plurality of electron tube stern assemblies.

One type of electron tube stem assembly comprises a flat glass disc through which extend a plurality of leadin wires. The portions of the lead-in wires extending from one face of the disc are adapted to serve as contact prongs of an electron tube of which the stem assembly is intended to be a part. The portions of the lead-in wires extending from the other face of the disc are adapted to serve as connecting means for connecting the prongs to appropriate electrodes of a completed electron tube.

In some electron tube applications, it is desirable to provide the portions of the lead-ins intended for use as connecting means, with a coating of silver. An advantageous way of applying the coating is by electrodeposition. In this manner of application, the stem assembly is supported so that the lead-in portions to be coated extend into a silver coating bath. A bar of silver is dis posed in the bath and connected to an electrical source of positive polarity. The free ends of the prong portions of the lead-ins are engaged by an electrode connected to a negative source of electrical polarity. Under these conditions, the portions of the lead-ins extending into the silver plating or coating bath, become coated with silver.

One difiiculty in the coating application referred to resides in the fact that the free ends of the prong portions of the lead-ins to be engaged by the negative electrode, may not always be in a common plane. Thus, one or more prongs of a stem assembly may extend farther from the disc of the assembly, than other prongs thereof. If, therefore, the negative electrode is in the form of a plate having a planar surface for engaging the prongs, it is capable of engaging only the longer prongs of the assembly. This leaves the connector elements of the shorter prongs without the desired coating.

This difiiculty is enhanced when a plurality of stem assemblies are simultaneously subjected to the selective coating procedure mentioned. It will be appreciated that coating a plurality of stem assemblies in one operation is desirable as increasing the speed of coating the assemblies and reducing the cost of tubes incorporating the coated assemblies.

According to one embodiment of the invention for A United States Patent 0 successfully meeting this difficulty, a plating or coating apparatus may be provided with a flat supporting member or plate having a plurality of apertures. The plate is preferably supported to be in a horizontal plane. A plurality of stem assemblies are supported on the upper surface of the plate, with the connector portions of the lead-ins extending downwardly through the apertures in the plate and into a silver coating bath. The prong portions of the lead-ins of the stem assemblies then extend upwardly. Since some variation characterizes the length of the prong portions of the lead-ins, the free ends of the prong portions do not all lie in a common plane. To provide electrical contact with each of the prong portions referred to, a planar electrode contact having a deformable conducting surface is caused to engage each of the free ends of the prong portions mentioned. To render the conducting surface referred to deformable, it is preferably formed by a mesh member of metal and provided with a resilient backing made of a material such as foam rubber. This resilient material is in turn provided with a backing of rigid material. The aforementioned electrode contact, resilient backing, and rigid backing constitute an electrode contact assembly.

This structure of the electrode contact assembly causes the conducting electrode contact thereof to conform itself to any irregularity in the array assumed by the free ends of the prong portions of the stem assemblies, and assures electrical contact between the electrode contact and all prongs of the assemblies.

Further objects and advantages of the invention will become apparent as the present description continues.

Referring to the drawing:

Figure l is a plan view of a coating apparatus embodying the invention;

Figure 2 is a sectional view along the line 22 of Figure 1; and

Figure 3 is a sectional view of an enlarged detail of the apparatus shown in Figure 1.

The apparatus shown in Figures 1 and 2 by Way of one example of practicing the invention, includes a tank 10 containing a silver coating bath 11 which may be silver cyanide in suitable solution well known in the art. Supported in tank 10 is a tray or basket 12 having a plurality of apertures 13 for providing communication between the tank It) and the interior of the basket 12.

Resting on the bottom of basket 12 are a plurality of silver bars 14 connected to an electrical source shown schematically, of positive polarity.

A tray 17 is adapted to receive a plurality of stem assemblies 19 shown best in Figure 3. These stem assemblies comprise a plurality of lead-ins extending through flat glass stems 20 and including relatively heavy prongs 21, and relatively thin leads 22 adapted to serve as connectors to electrodes of an electron tube. The silver coating bath 11 preferably extends upwardly to the lower surface of a stem disc supported on tray 17, so as to coat the entire length of the connectors 22. The silver bars 14 are preferably disposed in basket 12 in fiat-wise manner to present a maximum surface area to the array of connectors 22 extending from tray 18. A base 23 provides suitable support for the tank 10.

The tray 17 is supported in depending fashion by also trode contact assembly 24, by means of screws 25, 26 extending through marginal portions of the assembly referred to and thick side Wall 27 of the tray 17. The screws 25, 26 are provided with relatively large knurled heads for facility in separating the tray 17 from the electrode contact assembly 24.

The electrode contact assembly 24 includes a wire mesh electrode contact 28 made, for example, of stainless steel providing a planar lower surface. The electrode contact assembly 24 also includes a rigid plate 29 having a side 3 30. 'Between the plate 29 and mesh type electrode contact 28 is disposed a body of resilient material 31, such as foam rubber. The plate29 and electrode contact '28 are held together by engagement between a marginal portion of-the electrode contact and the outer surface of side 30 of the plate. This engagement may be in the form of aweld, and effectively confines the resilient material 31 between the plate 29 and electrode contact 28.

The electrode contact 28 of the electrode contact assemblyl 24 is connected to an electrical source of negative polarity shown schematically in Figure 2.

The plate 29 is fixed in a suitable manner to shaft 32 connected by coupling 33 to a motor 34, which is adapted to operate at a relatively slow speed. Energization of motor 34 causes thestructure comprising the electrode contact assembly 24 and tray 17 to rotatein the tray '12, and the coating bath 11, to thereby improve the coating application.

The motor is supported on a framework including uprights 35, 36 and transverse member 37, by suitable brackets 38, 39. The uprights 35, 36, are in turn fixed to feet 40, 41 having sufficient width for preventing tilting of the framework aforementioned. The feet referred to may rest on base 23.

"The sides 27 of the tray 17, extend upwardly a distance slightly less than the prongs 21 of the stern assemblies 19 mounted on the tray. Therefore, when the electrode contact assembly 24 is mounted on tray 17, the engagement between the electrode contact 28 and the upper edges of'the tray wall 27 will cause the electrode contact to become deformed bythe free ends of the prongs 21. Where two adjacent prongs are of an unequal length as shown in Figure 3, the deformation referred to will cause the electrode contact to engage both of such prongs. It will be noted that the deformation produced by the larger prong affects only the portion of the electrode .contact adjacent such prong. This limitation in deformation is assured by the rigid backing provided by plate 29. This limitation in deformation is advantageous in that it leaves an adjacent portion of the electrode contact unaffected and free to assume an independent deformation in response to an adjacent prong.

It is apparent from the foregoing that the invention provides an advantageous apparatus and method for coating a plurality of units simultaneously by electrodeposition and is of particularly utility in coating portions of a relatively large member of electron tube stem assemblies.

What is claimed is:

1. Apparatus for coating by electrodeposition connector wire portions extending from one face of a disc type stem assembly, compising a tank for containing a coating bath therein, a flat composite horizontally disposed structure including a fiat tray and a flat electrode contact assembly removably fixed to said tray and defining a space therebetween for receiving a plurality of disc type stem assemblies, said tray having a surface engaging portions of the discs of said assemblies, said tray having apertures in said surface through which said connector Wire portions are adapted to extend, said electrode contact assembly comprising an electrode contact having a conducting surface for engaging the free ends of prong Wire portions of said assemblies, a yieldable material engaging a surface of said contact opposite to said conducting surface, said conducting surface being yieldable against said yieldable material for accommodating said surface to prong wires of different lengths and for urging said discs against said tray surface, and means fixed to a surface of said electrode contact assembly opposite said conducting surface for removably supporting said composite structure horizontally in said container, and for rotating said composite structure on a vertical axis, whereby said connector wires only, are adapted to extend into said bath and said assemblies are securely supported on said composite structure for advantageously coating said connector wire portions.

2. Apparatus for coating by electrodeposition a plurality of spaced elongated metal units, comprising a coating container adapted to contain a coating bath, a flat tray adapted to support said units in spaced relation with portions of said units extending through said tray, a flat composite electrode contact assembly comprising a fiat body of resilient material, a rigid metal plate engaging one side of said resilient material and a wire mesh electrode contact engaging the other face of said material, means connecting said wire mesh electrode contact to one side of a source of current a marginal portion of said mesh electrode contact being fixed to said plate for supporting said body of resilient material between said metal plate and said electrode contact, means removably fixing said electrode contact assembly to said tray to form a structure wherein said wire mesh electrode contact is adapted to be deformed to engage simultaneously ends of all of said units, and means connected to said assembly structure for removably mounting the same in said container.

References Cited in the file of this patent Great Britain Jan. 16, 1930 

1. APPARATUS FOR COATING BY ELECTRODEPOSITION CONNECTOR WIRE PORTIONS EXTENDING FROM ONE FACE OF A DISC TYPE STEM ASSEMBLY, COMPISING A TANK FOR CONTAINING AA COATING BATH THEREIN, A FLAT COMPOSITE HORIZONTALLY DISPOSED STRUCTURE INCLUDING A FLAT TRAY AND A FLAT ELECTRODE CONTACT ASSEMBLY REMOVABLY FIXED TO SAID TRAY AND DEFINING A SPACE THEREBETWEEN FOR RECEIVING A PLURALITY OF DISC TYPE STEM ASSEMBLIES, SAID TRAY HAVING A SURFACE ENGAGING PORTIONS OF THE DISCS OF SAID ASSEMBLIES, SAID TRAY HAVING APERTURES IN SAID SURFACE THROUGH WHICH SAID CONNECTOR WIRE PORTIONS ARE ADAPTED TO EXTEND, SAID ELECTRODE CONTACT ASSEMBLY COMPRISING AN ELECTRODE CONTACT HAVING A CONDUCTING SURFACE FOR ENGAGING THE FREE ENDS OF PRONG WIRE PORTIONS OF SAID ASSEMBLIES, A YIELDABLE MATERIAL ENGAGING A SURFACE OF SAID CONTACT OPPOSITE TO SAID CONDUCTING SURFACE, SAID CONDUCTING SURFACE BEING YIELDABLE AGANIST SAID YIELDABLE MATERIAL FOR ACCOMMODATING SAID SURFACE TO PRONG WIRES OF DIFFERENT LENGTHS AND FOR URGING SAID DISCS AGAINST SAID TRAY SURFACE, AND MEANS FIXED TO A SURFACE OF SAID ELECTRODE CONTACT ASSEMBLY OPPOSITE SAID CONDUCTING SURFACE FOR REMOVABLY SUPPORTING SAID COMPOSITE STRUCTURE HORIZONTALLY IN SAID CONTAINER, AND FOR ROTATING SAID COMPOSITE STRUCTURE ON A VERTICAL AXIS, WHEREBY SAID CONNECTOR WIRES ONLY, ARE ADAPTED TO EXTEND INTO SAID BATH AND SAID ASSEMBLIES ARE SECURELY SUPPORTED ON SAID COMPOSITE STRUCTURE FOR ADVANTAGEOUSLY COATING SAID CONNECTOR WIRE PORTIONS. 